Dr. Stevens has been at Kansas State University for over 20 years researching flowers. He serves as the State Extension Specialist in Floriculture and is director of the Horticulture Research Center in Olathe, KS
Robin R. Dremsa is a Research
...

Dr. Stevens has been at Kansas State University for over 20 years researching flowers. He serves as the State Extension Specialist in Floriculture and is director of the Horticulture Research Center in Olathe, KS
Robin R. Dremsa is a Research Associate who manages the flower trials. She's been at the K-State Hort. Research & Extension Center since 2007.

While we hope your flowerbed is always healthy and in full-bloom, damaging diseases and insects can pop up unexpectedly. Here are some to look out for in your gardens.

Aster yellows

Echinacea (Coneflowers) with aster yellows disease

Aster yellows disease is spread by a small leafhopper insect. The population of leafhoppers dramatically increases shortly before the wheat crops are harvested in mid to late June. Check plants in your garden for the disease beginning around the first of July. Note the proliferation of mutated vegetative growth around the flower bud. There is no cure or treatment for the disease. You should remove infected plants immediately from your property and do not place into a compost pile. Read the K-State publication on aster yellows disease for more information and a list of susceptible cultivars.

Vinca (Catharanthus) with aster yellows disease.

Thrips

Thrips are extremely small insects that are difficult to see. Most often a distortion of the growing tips and flower buds are the first signs of their presence. Insecticidal sprays are effective in controlling the insect. Angelonia and vinca are useful as indicator species for the presence of thrips.

Angelonia with thrips damage.

Bud Worm

The larva, caterpillar stage, of a small moth's lifecycle feeds on the flower petals of several annual flower species. Petunia, geranium and calibrachoa are favored hosts. Damage from the bud worms seems to appear overnight. Plants that are beautifully flowering all of a sudden have no flowers. The insects have two to three lifecycles per growing season and can easily be controlled with insecticides. We apply a spinosad-containing insecticide on our flower trials to keep these pests in check.

Calibrachoa with bud worm damage.

Japanese Beetles

These pests seem to be increasing each year, and we find them congregating on the cannas and roses in the flower trials. The large beetles are easily seen while voraciously feeding on a wide variety of garden plants. KSUTurf's blog post about Japanese beetles has great information on the insect and various control methods.

Canna with Japanese Beetle damage.

Rose Rosette

Rose rosette disease causes unusual growth in roses like elongated stems, thick stems, excessive thorns, and other abnormalities. There is no cure for this disease, and you should remove plants, roots and all, from your garden and sterilize any tools that may have been in contact with an infected plant. Read K-State's publication on Rose Rosette for more detailed information.